1. Field
The presently disclosed subject matter relates to surface mount devices including LEDs, laser diodes, etc., and more particularly to a surface mount device with high reliability in which an electronic component can be reliably mounted on the die bonding pad by fixing it on both a die bonding pad and an insulating board exposed in a plurality of cutout sections with an adhesive material.
2. Description of the Related Art
Surface mount devices are frequently used for an electronic device such as a mobile phone, a personal computer and the like because they are small, light and can be directly mounted along with other electronic parts on a mounting board in a reflow soldering process.
However, surface mount devices should maintain high reliability so as not to break even when exposed to high temperature such as the environment present during a soldering process. The electronic device may become inoperable even if only one surface mount device breaks The broken device is difficult to replace because it is directly mounted along with the other electronic parts on the mounting board.
A conventional surface mount LED device is disclosed in Patent Document No. 1 (Japanese Patent Application Laid Open H11-046018). And also a conventional manufacturing method for surface mount devices is disclosed in Patent Document No. 2 (Japanese Patent Application Laid Open JP2007-207921).
FIG. 6 is a perspective view depicting a conventional surface mount LED device disclosed in Patent Document No. 1. The surface mount LED device includes: a circuit board that is made by forming conductor patterns 12 on surfaces of an insulating board 11; an LED chip 13 that is mounted on a die bonding pad 12a of the conductor patterns 12 via a conductive adhesive 14; and a bonding wire 15 for connecting an upper electrode of the LED chip 13 to a wire bonding pad 12b of the conductor patterns 12.
In addition, the surface mount LED device includes an encapsulating resin 16 that encapsulates both the LED chip 13 and the bonding wire 15 on the circuit board. Thus, the encapsulating resin 16 can prevent both the LED chip 13 and the bonding wire 15 from some problems caused by vibration, shock, dampness, etc, and can improve reliability of the surface mount LED device.
Furthermore, Patent Document No. 2 discloses and further characterizes the encapsulating resin 16. The encapsulating resin 16 can be composed of at least one of a transparent resin and a mixture resin, and the mixture resin includes a resin mixed with at least one of a diffuser, a phosphor, and a pigment for selectively absorbing light having a predetermined wavelength.
Therefore, the surface mount LED device can emit a direct light emitted from the LED chip 13 to the outside via the encapsulating resin 16 and also can emit a wavelength-converted light such as a white light and the like via the encapsulating resin 16.
However, the conventional surface mount LED device shown in FIG. 6 might cause a problem such as the LED 13 may not emit a light. One reason is that the conductor patterns 12 might peel from the encapsulating resin 16 and the LED chip 13 might peel from the die bonding pad 12a of the conductor patterns 12 along with the encapsulating resin 16.
The above-described problem may be caused after a reflow soldering process when mounting the surface mount LED devices on a mounting board and the like in the electronic devices. During the period when the devices are left in a high temperature environment, such as during the soldering reflow process, a difference of thermal expansion coefficient between the conductor patterns 12 and the encapsulating resin 16 might cause the above-described problems.
The surface mount LED device made according to the method disclosed in Patent document No. 2 may also cause a problem in that the LED device may have small variations with respect to the predetermined optical characteristics. The principal reason is that the conductive adhesive 14 may be drug upwards onto side surfaces of LED chip 3 that is located on a die bonding pad in a die bonding process and may be solidified on the side surfaces of LED chips 3.
Therefore, the solidified conductive adhesive 14 on the side surfaces of LED chip 3 might cause the above-described variations in optical characteristics. This is especially true when the LED device emits the wavelength-converted light to the outside via the encapsulating resin 16 of the mixture resin. In some cases, the conductive adhesive 14 on the side surfaces of LED chip 3 may cause a problem such as a non-uniform light distribution and the like.
The above-referenced Patent Documents are listed below, and are hereby incorporated with their English abstracts in their entireties.    1. Patent Document No. 1: Japanese Patent Application Laid Open H11-046018; and
Patent Document No. 2: Japanese Patent Application Laid Open JP2007-207921. The disclosed subject matter has been devised to consider the above and other problems features and characteristics. Thus, an embodiment of the disclosed subject matter can include a surface mount electronic device that can exhibit improved reliability by preventing various problems associated with exposure to high temperature such as during reflow soldering process, while reducing other associated problems of the conventional devices.